package 异常的学习;

import java.util.Scanner;
public class PTA3 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        try {
            int n = in.nextInt();
            if (n < 0) {
                throw new FuRutineException();
            }
            System.out.println(Math.sqrt(n));
        } catch (FuRutineException e) {
            System.out.println(e.getMessage());
        }
    }
}

class FuRutineException extends RuntimeException {
    public FuRutineException() {
        super("不能是负数");
    }
}
